Oct 4, 1990 - the risk related to hospital working conditions ... corded: standing up for long periods of time, ... all babies and among full-term babies only.
European Journal of Obstetrics & Gynecology and Reproductive 0 1991 Elsevier Science Publishers B.V. 0028-2243/91/$03.50
EUROBS
Biology,
40 (1991)
29-34
29
01121
High blood pressure during pregnancy and working conditions among hospital personnel Marie-Jo&phe
Saurel-Cubizolles i, Momclue Kaminski i, Christiane Josepha Llado i and Madeleine Estryn-Behar 2
’ INSERM,
Unite 149, Villejuif
and 2 Assistance
Accepted
Publique
for publication
des H6pitaux
4 October
de Paris,
Du Mazaubrun Paris,
‘,
France
1990
The relationship between working conditions and high blood pressure during pregnancy was analysed in a sample of 621 women hospital employees in the Paris region over the period 1979-1981. Data were collected by interviews during the routine medical visit at the end of postnatal leave. Women who had to work standing up for extended periods of time, who had to carry heavy loads or who had to perform heavy cleaning tasks had high blood pressure during their pregnancy more often than women not exposed to these working conditions. The accumulation of two out of the three or these three working conditions by the same woman was strongly related to high blood pressure. This relation remained significant when other risk factors of hypertension, such as age, parity, corpulence and tobacco use, were taken into account in a multiple logistic regression. Pregnancy;
High
blood
pressure;
Working
condition,
women;
Introduction Hypertension during pregnancy and its complications are considered to be one of the main causes of low birth weight, fetal distress and perinatal deaths [l]. Several authors have investigated medical risk factors, medical complications of a high blood pressure during pregnancy [2,3] and problems about treatment [4,5]. Very few have studied environmental conditions of pregnant women which could be related to high blood pressure. Several studies have shown the risk for pregnancy outcome - preterm delivery, low birth-
Correspondence: 149, 16 Avenue France.
Dr. MJ Saurel-Cubizolles, INSERM Paul Vaillant Couturier, 94807 Villejuif
Unite Cedex,
Hospital
personnel
weight - among hospital personnel, and especially the risk related to hospital working conditions [6,7]; risks associated with working conditions have also been found in other occupational groups
Fwl. This study was carried out in order to analyse the relationship between working conditions and high blood pressure among pregnant women working in hospital. Population and Methods A survey was conducted in seven of the main public hospitals in the Paris region over the period 1979-1981. It included all the women who had worked in these hospitals during their pregnancy, except for doctors. The data were collected by the occupational health practitioners of the hospital
30
staff by interviewing the women during their routine medical visit before resuming work at the end of postnatal leave. The data covered their occupation, working conditions, social characteristics, medical history, pregnancy, delivery, and status of the infant at birth. Women who had worked less than 13 weeks during their pregnancy, or for whom the duration of work was unknown, and women who had resumed their work later than 36 weeks after delivery were excluded from the study; the final sample included 621 women. This study compares the rate of high blood pressure found among women under diverse working conditions during their pregnancy. The following working conditions were systematically recorded: standing up for long periods of time, carrying heavy load, heavy cleaning tasks, nursing tasks, number of patients, climbing stairs often, night work and number of hours worked each week. Occupational category (nurses, auxiliaries, ancillary staff and others) and type of department (medicine, radiology, kitchen, administration etc) were also recorded. High blood pressure was defined as systolic blood pressure > 130 mmHg and/or diastolic blood pressure > 80 mmHg on at least one occasion during pregnancy. Relationships between high blood pressure and working conditions were analysed after controlling for several factors known to be related to hypertension among pregnant women. For multivariate analysis, the following factors were used as dichotomous variables. Quetelet’s index (pre-pregnancy weight/height2) was used as a measure of relative body weight: not overweight (less or equivalent to the 90th percentile) and overweight (higher than the 90th percentile); in this sample, the 90th percentile of the Quetelet index was 25.4 kg/m’. Women’s age, parity and tobacco use were classified as: 35 or more and less than 35, primiparous and multiparous women, non-smoker and smoker. Data about coffee and alcohol consumption were also obtained during the interview by determining the number of cups of coffee or drinks each woman drank per day. The statistical methods used were Pearson (X-square test to compare percentages and Student’s t-test to compare mean values. Logistic regression analysis was used to examine the as-
sociation between working conditions and high blood pressure while controlling for confounders. Results High blood pressure during pregnancy as defined in this study was reported by 14.5% of the women. This indicator of hypertension was related to several characteristics of the development and outcome of the pregnancy. Women with high blood pressure were more often on sick-leave, hospitalised and had caesarean sections more often (Table I). The percentage of newborn babies weighing less than 2500 g was higher among women with hypertension; this difference was observed among all babies and among full-term babies only. Three working conditions and their accumulation by the same women were related to high blood pressure: standing-up position, carrying heavy loads and heavy cleaning tasks (Table II). The other working conditions recorded in the survey were not significantly related to high blood pressure. Although there was no relationship between occupational category and high blood pressure, women who worked in radiology departments or general services (such as kitchen, laundery etc.) had a significantly higher rate of high blood pressure: 21% instead of 14% among women working in medical departments and 7% among women working in laboratories or administrative services TABLE
I
Wigh blood
pressureand
development
and
outcome
of preg-
nancy High blood pressure
Number of women Sickleave during pregnancy (%) Hospitalisation preww Caesarean
P
Yes
No
90
531
86
11
< 0.06
36
11
-=z 0.001
24
14
< 0.01
6 2
< 0.01 i 0.001
during (%) section
(%)
Birthweight lower than 2500 g (W) all children 14 full-term children 6
31 TABLE High tions
II blood
TABLE pressure
in pregnancy
according
Women with high blood pressure
Long
standing-up
yes no Carrying yes
heavy
IlO
Heavy yes no
cleaning
Accumulation none 1 2 3
to working
%
position 291 326
19 10
< 0.01
loads 116 481
24 12
< 0.001
tasks 96 507
26 12
< 0.001
strenuous 11 10 25 44
Number of women Age (years) Number of children before this pregnancy Quetelet’s index (kg/m2) Smoking habit (W) No cigarettes/day (smokers only)
for women
blood
pressure
accord-
P
yes
IlO
90 27.7
531 27.3
0.7 23.1 9.0
0.6 21.3 16.1
n.s. < 0.001 ns.
5.5
9.4
i 0.05
n.s.
n.s., not significant
working
(P < 0.05). But this association the differences in the working tioned above. After adjusting for of strenuous working conditions,
Mean
of hypertension in pregnancy High
conditions
*
high blood pressure rates between the departments was no longer significant. Several characteristics are known to be risk factors for hypertension during pregnancy. Table III shows that the Quetelet’s index was significantly higher for women who had high blood pressure. The percentage of smokers was lower among hypertensive women, but this difference was not significant, and the number of cigarettes for smokers was lower. No relation was found with age and parity (Table III). There was no difference in the rate of high blood pressure according to usual daily intake of coffee and alcohol - number of drinks of beer, wine, liquor etc.
i 0.001
* Accumulation of the three strenuous working conditions: long standing-up position, carrying heavy loads, heavy cleaning tasks. The indicator varies from 0 to 3 according to whether the occupation involves none, one, two or all three strenuous working conditions.
TABLE
III
Mean values of risk factors ing to high blood pressure
P
n
of the three 246 231 87 27
condi-
was explained by conditions menthe accumulation the difference in
IV values
of risk factors
Number of women Age (ye=4 Number of children before Quetelet’s index (kg/m2) Smoking habit (%) No cigarettes/day (smokers
of hypertension
this pregnancy
only)
according
to accumulation
of strenuous
working
Accumulation of the three working conditions *
strenuous
none
two or three
or one
417 27.4 0.6 21.3 14.9 9.6
* Accumulation of three strenuous working conditions: long standing-up indicator varies from 0 to 3 according to whether the occupation involves n.s., not significant.
114 27.2 0.8 22.4 14.3 8.5
conditions
in pregnancy P
n.s. ns. < 0.001 n.s. n.s.
position, carrying heavy loads, heavy none, one, two, or all three strenuous
cleaning working
tasks. The conditions.
32 TABLE Risk
V factors
of high blood
pressure:
logistic
regression
analysis
Variable Accumulation of two or the three No tobacco use Primiparity Age > 35 Quetelet’s Index > 90th percentile
working
* Accumulation of three strenuous indicator varies from 0 to 3 according n.s., not significant.
conditions
*
working conditions: long to whether the occupation
Age, parity and tobacco use were not significantly related to the indicator of strenuous working conditions (Table IV). The Quetelet’s index was higher for women who cumulated two out of the three or all three working conditions described above. This characteristic could be a confounder in the studied relationship. When controlling for age, parity, tobacco use and corpulence index in a logistic regression, the accumulation of strenuous working conditions remained significantly related to high blood pressure (Table V). Discussion These results suggest that the accumulation of physically arduous working conditions by the same women during their pregnancy is associated with high blood pressure among hospital workers. All women who had worked less than one trimester during their pregnancy have been excluded. Most of them had stopped working very early on in their pregnancy due to medical reasons, and therefore they already constituted a group at high-risk, independently from their work. Women returning to work later than 36 weeks after delivery have also been systematically excluded from the study. Under French law, the usual postnatal leave lasts 10 weeks for the first and the second child in the family and 18 weeks for subsequent children. After this postnatal leave, women may choose to take a parental leave for one, two or three years after the birth. For the women returning to work long after the birth, the elapsed time between the work interruption and
Adjusted odds ratio
95% confidence
3.30 2.51 1.20 1.72 2.58
1.97-5.41 1.04-6.05 0.73-2.01 0.73-4.06 1.32-5.05
standing involves
position, carrying none, one, two,
P limits
heavy loads, heavy or all three strenuous
i 0.001 i 0.05 n.s. n.s. i 0.01 cleaning working
tasks. The conditions.
the interview could lead to a lack of accuracy in the data collected. The aim of this survey was to study preterm delivery rate according to working conditions [7]. However, as very few studies have been published about hypertension during pregnancy and working conditions, it seems useful to raise this question from these data, in spite of the limited information available on blood pressure. In this survey there was only one question about blood pressure which was: “did you have one or more readings of blood pressure higher than 13/8?” (130 mmHg for systolic and/or higher than 80 mrnHg for diastolic blood pressure). High blood pressure according to this definition was reported by the women themselves. It is evident that these blood pressure checks were performed by several practitioners, using various manometers, in different positions of the women at several different stages of the pregnancy. This indicator of hypertension corresponds to the information that we could get in the usual practice of antenatal care in a general population. In addition, BrCart et al. [12] demonstrated that a single high blood pressure reading during pregnancy was associated with a higher risk of fetal growth retardation. In this sample, we observed that this indicator was related to low birth weight, which is a well known consequence of hypertension during pregnancy [12-151. Hence, this definition of high blood pressure may be considered a good indicator of hypertensive disorders, even if it does not correspond to the usually admitted and rigorous definition [16]. Data about blood pressure before the beginning of the pregnancy and
33
after the delivery were not available; we camot assess that reported high blood pressure was pregnancy-induced or chronic hypertension, but we show from these data that this hypertension was related to the management and the outcome of the pregnancy. For this reason its risk factors have to be identified. The risk factors of hypertension described in the literature have been considered in this study. High blood pressure was more frequent among obese women [13,17], this result was clearly confirmed in this study. No relationship was found between age, parity and high blood pressure. A number of studies have reported that primiparous women have a higher risk of hypertension [17,18]. Likewise, pregnant women aged 35 or over have hypertension more frequently, which is probably a reflection of essential hypertension. Our study was limited to working pregnant women who are more often in intermediate age groups: less often under 20 or above 34 than pregnant women without occupation [19]. Thus, women exposed to high blood pressure because of their age were not numerous in our sample, this could explain the absence of such a relationship. Women who smoked during pregnancy had a lower rate of high blood pressure. These data are consistent with the results of other studies, among pregnant women [20] as well as among the general population [21]. Among the general population, relationships between hypertension and alcohol or caffeine consumption have been discussed [21]. The results showed an increase in blood pressure for a short time after coffee absorption, and provided strong evidence that hypertension and alcoholism are associated. In our sample, the consumption of coffee and alcohol during pregnancy reported by the women was very low. Several studies found a higher rate of hypertension among socially under-privileged pregnant women [18], a result that is often observed in the general population as well [22]. Among hospital personnel, a good indicator of socio-economic status may be the women’s occupational level. A higher rate of hypertension has not been found among less qualified occupations. However, any comparison of occupations must consider that the
.working conditions found in underprivileged occupations are often more strenuous than those of privileged occupations. Among known risk factors of hypertension, only the corpulence index was related to working conditions: women with physically arduous conditions had a higher corpulence index. However, even after controlling adiposity, the rate of high blood pressure remained higher among women exposed to arduous working conditions. Little is known about the relationships between hypertension and physical working conditions. Fouriaud et al. [22] reported an increase in blood pressure for workers with a heavy physical work load, for those working in a standing-up position and for women with irregular schedules. These relationships were partly explained by occupational group. However, in this study assembly line work was related to an increase in blood pressure among manual workers. Very few studies have analysed the effect of working conditions on hypertension among pregnant women. In France, on a national sample of births, we observed a significant relationship between hypertension and the carrying of heavy loads and noise. These relationships remained statistically significant, even after adjustment for age, parity, smoking habits and weight/height index [23]. A survey carried out in the West of France among 198 pregnant women working in hospitals showed that when the women who were treated for hypertension were compared to those who were not, there was a greater number of women in the hypertensive group who held jobs which required standing for long periods of time, carrying heavy loads and performing heavy cleaning tasks [24]. In another study of 204 women working in hospitals during their pregnancy, a long period of standing-up and carrying heavy loads were related to hypertension [6]. The trend was the same for cleaning tasks. All the data in these studies show consistent evidence regarding the relationship between long work, and the carrying of heavy loads and high blood pressure in pregnancy. The study on ‘high blood pressure during pregnancy and working conditions’ presented in this paper gives preliminary information which needs
34
to be confirmed through further research. The method used to conduct the study, along with the retrospective data which were obtained on blood pressure and working conditions, incite us to carefully examine these results, despite the fact that they correspond to findings in the literature. Moreover, working conditions have been analysed along with other characteristics of pregnancy: spontaneous abortions, perinatal mortality, preterm birth or low birthweight [g-11]. A standingup position and the carrying of heavy loads have been found to be risk factors in the outcome of pregnancy, more specifically on preterm delivery. So, if they are confirmed, the results of our study would have consequences with regard to the prevention of hypertension during pregnancy for women working outside the home, and various other disorders could be prevented by the same measures. Acbowledgments The authors acknowledge 6. B&art for his helpful advice in this study, all occupational health practitioners who contributed to the collection of data, K. Bean for help with the translation and M.C. Nourry and M. Corre who typed this paper. References World Health Organisation. Arterial Hypertension. Geneva: WHO, 1978 (Technical report series No. 628). Bonnar J, MacGillivray I, Symonds EM. Pregnancy hypertension. Lancaster: MTP Press, 1980. Plouin PF, Chatellier G, Brtart G et al. Factors predictive of perinatal outcome in pregnancies complicated by hypertension. Em J Obstet Gynecol Reprod Biol 1986;23:341348. Hogs&t S, Lindmark G, Lindberg B. Methodological problems in studies on hypertension therapy during pregnancy. Acta Obstet Stand 1984;Suppl 118:39-42. Plouin PF, Breart G, Maillard F, Papiemik E, Relier JP, The Labetalol Methyldopa Study Group. Comparaison of antihypertensive efficacy and perinatal safety of labetalol and methyldopa in the treatment of hypertension in pregnancy: a randomized controlled trial. Br J Obstet Gynaecol 1988;95:868-876. 6 Estryn M, Kaminski M, Franc M, Fermand S, Gerstle F. Grossesse et conditions de travail en milieu hospitalier. Rev Franc Gynecol 1978;73:625-631. 7 Saurel-Cubizolles MJ, Kaminski M, Llado-Arkhipoff J et al. Pregnancy and its outcome among hospital personnel
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13 MacGillivray I. Hypertension in pregnancy and its consequences. J Obstet Gynaecol Br Commenw 1961;68:557-569. 14 Naeye RL. Maternal blood pressure and fetal growth. Am J Obstet Gynecol 1981;141:780-787. 15 Svenningsen NW, Liedholm H, Aberg A. Hypertension in pregnancy and the infant: a controlled follow-up study. Acta Obstet Gynecol Stand 1984;Suppl118:103-106. 16 Davey DA, MacGillivray I. The classification and definition of the hypertensive disorders of pregnancy. Am J Qbstet Gynecol 1988;158:892-898. 17 Andersch B, Svensson A, Hansson L. Characteristics of hypertension in pregnancy. Acta Obstet Gynecol Stand 1984, Suppl 118:33-38. 18 Organisation Mondiale de la Sante. Les troubles tensionnels de la grossesse. Geneve: OMS, 1987 (technical report series No. 758). 19 Saurel-Cubirolles MJ, Kaminski M, Rumeau-Rouquette C. Activite professionnelle des femmes enceintes, surveillance prenatale et issue de la grossesse. J Gynecol Obstet Biol Repr 1982;11:959-967. 20 Scott-Russel C, Taylor R, Law CE. Smoking in pregnancy, maternal blood pressure, pregnancy outcome, baby weight and growth and other related factors. Br J Prev Sot Med 1968;22:119-126.
21 Arkwright PD, Beilin LJ, Rouse I, Armstrong BK, Vandongen R. Effects of alcohol use and other aspects of lifestyle on blood pressure levels and prevalence of hypertension in a working population. Circulation, 1982;66:6066. 22 Fouriaud C, Jacquinet-&lord MC, Degoulet P et al. Influence of socioprofessional conditions on blood pressure levels and hypertension control. Am J Epidemiol 1984;12:72-86. 23 Saurel-Cubizolles MJ, Kaminski M, Du Mazaubmn C, Breart G. Les conditions de travail professionnel des femmes et l’hypertension arterielle en cours de grossesse. Rev Epidem Sante Publique, 1991, in press. 24 Crespy M. Grossesses et conditions de travail a propos de 198 agents du Centre Hospitalier Regional de Rennes. These de MCdecine, Rennes, 1983.
